JP7071854B2 - Constant velocity universal joint - Google Patents

Description

The present disclosure relates to a constant velocity universal joint that connects rotary drive shafts to each other.

Some universal joints transmit torque from the outer race or inner race on the input side to the inner race or outer race on the output side via a plurality of balls. A plurality of track grooves for accommodating the ball are formed in the outer race and the inner race of the constant velocity universal joint. The torque is transmitted at the contact point between the ball and the track groove. Therefore, a large torque load is likely to be applied to the contact point between the ball and the track groove. The surface pressure due to this torque load affects the life of the constant velocity universal joint.

Patent Document 1 and Patent Document 2 have an object of reducing the surface pressure, and form a Gothic arch-shaped Gothic arch portion at the bottom of the groove. As a result, the ball and the track groove can be brought into multipoint contact at a plurality of points of three or more, and the surface pressure can be dispersed to a large number of contact points.

Japanese Unexamined Patent Publication No. 2007-271040 Japanese Unexamined Patent Publication No. 2005-201371

By the way, as shown in FIG. 8, when the rotational driving force is transmitted to the outer race 4, the outer race 4 is slightly displaced in the twisting direction with respect to the inner race 5, and the ball 6 and the track grooves 9 and 15 are displaced. The center PC of the contact P is moved from the groove bottom side in the groove width direction. At this time, the contact point P between the ball 6 and the track grooves 9 and 15 has an elliptical shape that is long in the circumferential direction of the track grooves 9 and 15. The area of the elliptical contact P depends on the ratio of the radius of the ball 6 to the radius of the track grooves 9 and 15, and becomes larger as the radius of the track grooves 9 and 15 is closer to the radius of the ball 6. The larger the area of the contact P, the lower the surface pressure due to the torque load.

However, when the contact P protrudes from the arc portions 11 and 17 formed on both sides of the Gothic arch portions 10 and 16, the area of the contact P becomes small and the surface pressure due to the torque load increases. In this case, there is a problem that contact stress tends to be concentrated in the vicinity of the opening edges 13 and 19 of the track grooves 9 and 15 in the torque load direction. Further, when the input side and the output side have a relative intersection angle, the ball 6 has a rolling speed at the same time as receiving a torque load, and the surface pressure of the contact P is not constant due to the torque fluctuation during one rotation. .. For this reason, flaking is likely to occur in the vicinity of the opening edges 13 and 19 of the track grooves 9 and 15 where the contact stress is concentrated, which hinders the extension of the life of the constant velocity universal joint.

Therefore, the present disclosure has been devised in view of such circumstances, and an object thereof is to provide a constant velocity universal joint capable of suppressing stress concentration in the vicinity of the opening edge of a track groove.

According to one aspect of the present disclosure, an outer race having a cylindrical shape and an outer peripheral side track groove extending in the axial direction formed on the inner peripheral surface, and an inner peripheral side track accommodated in the outer race and extending in the axial direction. A constant-velocity universal joint including an inner race having a groove formed on the outer peripheral surface and a ball accommodated in the inner peripheral side track groove and the outer peripheral side track groove.
At least one of the inner peripheral side track groove and the outer peripheral side track groove has a Gothic arch portion formed in a Gothic arch shape at the bottom of the groove and an arc formed in an arc shape on both sides of the Gothic arch portion. With a department,
The Gothic arch portion is formed within an angle of 20 ° or more and 35 ° or less from the center of the groove bottom centered on the center of the ball.
Provided is a constant velocity universal joint characterized in that the radii of the two arcuate surfaces constituting the Gothic arch portion are set to be 0.1% or more and 0.3% or less larger than the radius of the ball.

Preferably, both the inner peripheral side track groove and the outer peripheral side track groove may include the Gothic arch portion and the arc portion.

Preferably, the radius of the arc portion is formed to be larger than the radius of the arc surface.

Preferably, the inner race is formed so as to be slightly movable in the axial direction and the radial direction with respect to the outer race.

Further, the inner race may be formed so as not to be movable in the axial direction and the radial direction with respect to the outer race.

According to the present disclosure, stress concentration in the vicinity of the opening edge of the track groove can be suppressed.

It is a side sectional view of the constant velocity universal joint which concerns on one Embodiment of this disclosure. It is an exploded perspective view of a constant velocity universal joint. It is a front view of the inner race. It is a front view of the outer race. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is an enlarged explanatory view of the main part of FIG. It is a schematic diagram explaining the operation of a constant velocity universal joint. It is a schematic diagram of the comparative example of a constant velocity universal joint.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

FIG. 1 is a schematic side sectional view of a constant velocity universal joint according to the present embodiment. FIG. 2 is an exploded perspective view of the constant velocity universal joint shown in FIG. 1.

As shown in FIGS. 1 and 2, the constant velocity universal joint 1 connects the input shaft 2 and the output shaft 3 flexibly. The constant velocity universal joint 1 is used, for example, for a propeller shaft of a vehicle, a drive shaft, or the like.

The constant velocity universal joint 1 includes a tubular outer race 4 connected to an input shaft 2, an inner race 5 housed in the outer race 4, and a plurality of balls interposed between the outer race 4 and the inner race 5. 6 and a cage 7 for holding the ball 6.

The ball 6 is formed of a metal such as steel into a perfect sphere.

The cage 7 is formed in a cylindrical shape, and the outer peripheral surface 7a and the inner peripheral surface 7b are formed in a spherical shape. Further, the cage 7 is formed with a plurality of ball windows 7c in the circumferential direction for projecting a part of the balls 6 located on the inner peripheral side toward the outer peripheral side.

The outer race 4 has a flange 4a at one end in the axial direction. The flange 4a is fastened to the input shaft 2. The flange 4a may be fastened to an output shaft (not shown). In this case, an input shaft (not shown) is spline-fitted to the inner race 5 described later. A boot 8 is provided at the other end of the outer race 4 in the axial direction. Further, the inner peripheral surface 4b of the outer race 4 is formed so that the inner diameter at the center in the axial direction is larger than the inner diameters at both ends in the axial direction.

Further, on the inner peripheral surface 4b of the outer race 4, an outer peripheral side track groove 9 for accommodating the ball 6 protruding on the outer peripheral side of the cage 7 is formed so as to extend in the axial direction. A plurality of outer peripheral side track grooves 9 are formed in the circumferential direction of the outer race 4. Specifically, a plurality of outer peripheral side track grooves 9 are formed at equal intervals in the circumferential direction of the outer race 4. All of these outer peripheral side track grooves 9 are formed in the same shape (rotational symmetry).

As shown in FIG. 1, the inner peripheral surface 4b and the outer peripheral side track groove 9 of the outer race 4 are formed in an arc shape when viewed from the circumferential direction. Specifically, when the center of the arc forming the inner peripheral surface 4b of the outer race 4 is the first center O _4b and the center of the arc forming the outer peripheral side track groove 9 is the second center O ₉ , the second center is the second. The center O ₉ is offset in the axial direction closer to the flange 4a than the first center O _4b .

As shown in FIGS. 3, 5 and 6, the outer peripheral side track groove 9 is formed in a Gothic round shape when viewed from the front in the axial direction. In the present embodiment, the Gothic R shape means a shape in which a plurality of arcs are combined to form a substantially arc shape, and in particular, it has a pointed arch shape (Gothic arch shape) portion in which two arcs are overlapped. Say something.

The outer peripheral side track groove 9 is a Gothic arch portion 10 formed at the bottom of the groove and formed in a Gothic arch shape, and an arc portion 11 formed on both sides of the Gothic arch portion 10 in the circumferential direction and formed in an arc shape. And.

The Gothic arch portion 10 is formed within a range in which the angle (connecting angle) θ from the groove bottom center BC centered on the ball center O is 20 ° or more and 35 ° or less.

Further, the radius R1 of the two arcuate surfaces 12 constituting the Gothic arch portion 10 is set to be 0.1% or more and 0.3% or less larger than the radius R of the ball 6.

Further, the circular center O1 of the arc surface 12 is arranged so as to be offset from the ball center O in the groove width direction X, and is separated from the groove bottom center BC in the direction Y orthogonal to the groove width direction X from the ball center O. It is placed in the correct position. Here, the circle center O1 of the arc surface 12 means the center of the circle at the radius R1 of the arc surface 12. Further, the circular center O1 of the arc surface 12 is located on the opposite side of the arc surface 12 with the line connecting the groove bottom center BC and the ball center O as a boundary in the groove width direction.

The arc portion 11 is formed to have the same diameter or a larger diameter as the two arc surfaces 12 constituting the Gothic arch portion 10. That is, the relationship between the radius R2 of the arc portion 11, the radius R1 of the arc surface 12, and the radius R of the ball 6 is R2 ≧ R1> R. However, the difference between the radius R2 of the arc portion 11 and the radius R of the ball 6 is extremely small. As a result, the contact point P (see FIG. 7) when the arc portion 11 and the ball 6 come into contact becomes an elliptical shape that is long in the circumferential direction, and the ball 6 and the arc portion 11 are larger than when the difference between the radius R2 and the radius R is large. The contact area with can be increased.

By forming the Gothic arch portion 10 as described above, the Gothic arch portion 10 is kept away from the opening edge 13 of the outer peripheral side track groove 9 while sufficiently ensuring the clearance (vertical clearance) between the Gothic arch portion 10 and the ball 6. be able to. The vertical clearance functions as an oil reservoir for lubricating oil.

As in the comparative example shown in FIG. 8, if the Gothic arch portion 10 is close to the opening edge 13 of the outer peripheral side track groove 9, the dimension of the arc portion 11 in the circumferential direction becomes small. In this case, when the ball 6 that has received the torque rises up to the arc portion 11, the central PC of the contact P having a high surface pressure suddenly approaches the opening edge 13 of the outer peripheral side track groove 9, and the surface of the opening edge 13 The pressure rises sharply. Further, since the contact point P between the ball 6 and the arc portion 11 has an elliptical shape long in the circumferential direction, it easily protrudes outside the arc portion 11. When the contact P protrudes outside the arc portion 11, the area of the contact P becomes narrow, the surface pressure increases in the entire contact P, and stress concentration tends to occur in the vicinity of the opening edge 13 of the outer peripheral side track groove 9.

However, the constant velocity universal joint 1 according to the present embodiment keeps the Gothic arch portion 10 away from the opening edge 13 of the outer peripheral side track groove 9. Therefore, as shown in FIG. 7, even when the ball 6 rises to the arc portion 11, it is possible to prevent the center PC of the contact P from suddenly approaching the opening edge 13 of the outer peripheral side track groove 9, and the opening edge can be prevented. It is possible to prevent or suppress the sudden increase in the surface pressure of 13. Then, it is possible to suppress the contact P from protruding from the arc portion 11, and it is possible to further suppress the surface pressure acting on the vicinity of the opening edge 13 of the outer peripheral side track groove 9 from further increasing, and it is possible to suppress the vicinity of the opening edge 13 of the outer peripheral side track groove 9. It is possible to prevent or suppress the tendency of stress concentration to occur.

As shown in FIGS. 1, 2 and 4, the inner race 5 is formed in a substantially cylindrical shape. A plurality of spline grooves 14 spline-fitted to the output shaft 3 are formed on the inner peripheral surface 5a of the inner race 5 in the circumferential direction. The outer peripheral surface 5b of the inner race 5 is formed to have a larger outer diameter at the center in the axial direction than at both ends in the axial direction. On the outer peripheral surface 5b of the inner race 5, an inner peripheral side track groove 15 for accommodating the ball 6 located on the inner peripheral side of the cage 7 is formed so as to extend in the axial direction. A plurality of inner peripheral side track grooves 15 are formed in the circumferential direction of the inner race 5. Specifically, a plurality of inner peripheral side track grooves 15 are formed at equal intervals in the circumferential direction (the same number as the outer peripheral side track grooves 9). All of these inner peripheral side track grooves 15 are formed in the same shape (rotational symmetry).

As shown in FIG. 1, the outer peripheral surface 5b and the inner peripheral side track groove 15 of the inner race 5 are formed in an arcuate cross section when viewed from the circumferential direction. Specifically, when the center of the arc forming the inner peripheral side track groove 15 is the third center O ₁₅ , the third center O ₁₅ is in a direction away from the flange 4a in the axial direction from the first center O _4b . It is offset (in the direction opposite to the second center O ₉ ).

As shown in FIGS. 4, 5 and 6, the inner peripheral side track groove 15 is formed in a Gothic round shape when viewed from the front in the axial direction. The inner peripheral side track grooves 15 are formed in the same number as the outer peripheral side track grooves 9 so as to be paired with the outer peripheral side track grooves 9. Further, the inner peripheral side track groove 15 is formed symmetrically inward in the radial direction with respect to the opposite outer peripheral side track groove 9.

The inner peripheral side track groove 15 is a Gothic arch portion 16 formed at the bottom of the groove and formed in a Gothic arch shape, and an arc portion formed on both sides of the Gothic arch portion 16 in the circumferential direction and formed in an arc shape. 17 and.

The Gothic arch portion 16 is formed within a range in which the angle (connecting angle) θ from the groove bottom center BC centered on the ball center O is 20 ° or more and 35 ° or less.

Further, the radius R1 of the two arcuate surfaces 18 constituting the Gothic arch portion 16 is set to be 0.1% or more and 0.3% or less larger than the radius R of the ball 6.

Further, the circular center O1 of the arc surface 18 is arranged so as to be offset from the ball center O in the groove width direction X, and is arranged at a position separated from the ball center O and the groove bottom center BC in the Y direction. Further, the circular center O1 of the arc surface 18 is located on the opposite side of the arc surface 18 with the line connecting the groove bottom center BC and the ball center O as a boundary in the groove width direction.

The arc portion 17 is formed to have a diameter larger than the two arc surfaces 18 constituting the Gothic arch portion 16.

By forming the Gothic arch portion 16 as described above, the Gothic arch portion 16 is formed from the opening edge 19 of the inner peripheral side track groove 15 while sufficiently ensuring the clearance (vertical clearance) between the Gothic arch portion 16 and the ball 6. You can keep it away.

As a result, as shown in FIG. 7, even when the ball 6 receiving the torque rises up to the arc portion 17, the center PC of the contact P suddenly approaches the opening edge 19 of the inner peripheral side track groove 15. It can be suppressed, and it is possible to prevent or suppress the sudden increase in the surface pressure of the opening edge 19. Then, it is possible to suppress the contact P from protruding from the arc portion 17, and it is possible to suppress the surface pressure acting on the vicinity of the opening edge 19 of the inner peripheral side track groove 15 from further increasing, and it is possible to suppress the surface pressure acting on the vicinity of the opening edge 19 of the inner peripheral side track groove 15 to be further suppressed. It is possible to prevent or suppress the tendency of stress concentration to occur in the vicinity of 19.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure may also include the following other embodiments.

(1) In the above-described embodiment, the case where the constant velocity universal joint 1 is a fixed constant velocity universal joint in which the inner race 5 cannot move in the axial direction with respect to the outer race 4 has been described, but the present invention is limited to this. It's not a thing. The constant velocity universal joint 1 may be a sliding constant velocity universal joint in which the inner race 5 can move in the axial direction with respect to the outer race 4.

(2) The output shaft 3 is spline-fitted to the inner race 5, but is not limited to this. For example, the inner race 5 may be integrally provided with the output shaft 3 by welding or the like. In this case, the inner race 5 may be formed in a columnar shape.

(3) It is assumed that the Gothic arch portions 10 and 16 are formed in both the inner peripheral side track groove 15 and the outer peripheral side track groove 9, but the Gothic arch portions 10 and 16 are formed in only one of them. May be good. In this case, the other may be formed in an arc shape when viewed from the front.

(4) The input shaft 2 is connected to the outer race 4 and the output shaft 3 is connected to the inner race 5, but conversely, the input shaft 2 is connected to the inner race 5 and the output shaft 3 is connected to the outer race 4. May be connected to.

The configurations of each of the above embodiments can be partially or wholly combined, as long as there is no particular contradiction. The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the scope of claims are included in the present disclosure. Therefore, this disclosure should not be construed in a limited way and may be applied to any other technique that belongs within the scope of the ideas of this disclosure.

1 Constant velocity universal joint 4 Outer race 4b Inner peripheral surface of outer race 5 Inner race 5b Outer surface of inner race 6 Ball 7 Cage 9 Outer outer track groove 10 Gothic arch part 11 Arc part 12 Arc surface 15 Inner peripheral side track groove 16 Gothic Arch 17 Arc 18 Arc Surface BC Groove Bottom Center O Ball Center O 1 Arc Surface Center R Ball Radius R1 Arc Surface Radius R2 Arc Arc Radius

Claims (4)

An outer race that is formed in a cylindrical shape and has an outer peripheral side track groove that extends in the axial direction on the inner peripheral surface, and an inner race that is housed in the outer race and has an inner peripheral side track groove that extends in the axial direction on the outer peripheral surface. A constant-velocity universal joint including a ball accommodated in the inner peripheral side track groove and the outer peripheral side track groove.
At least one of the inner peripheral side track groove and the outer peripheral side track groove has a Gothic arch portion formed in a Gothic arch shape at the bottom of the groove and a Gothic arch portion formed in both sides of the Gothic arch portion in a circular arc shape. It is provided with an arc portion located between the arch portion and one of the opening edges .
The Gothic arch portion is formed within an angle of 20 ° or more and 35 ° or less from the center of the groove bottom centered on the center of the ball.
The radius of the two arcuate surfaces constituting the Gothic arch portion is set to be 0.1% or more and 0.3% or less larger than the radius of the ball.
The radius of the arc portion is formed to be larger than the radius of the arc surface.
A constant velocity universal joint that is characterized by this. The constant velocity universal joint according to claim 1, wherein both the inner peripheral side track groove and the outer peripheral side track groove include the Gothic arch portion and the arc portion. The constant velocity universal joint according to claim 1 or 2 , wherein the inner race is formed so as not to be movable in the axial direction with respect to the outer race. The constant velocity universal joint according to claim 1 or 2 , wherein the inner race is formed so as to be movable in the axial direction with respect to the outer race.

Images